Questions tagged [seismic]
The seismic tag has no usage guidance.
93
questions
6
votes
2
answers
97
views
How to produce random numbers from seismic data?
I have read that the University of Chile uses seismic data to produce random numbers. (https://random.uchile.cl/randomness-beacon). Does seismic data real have randomness and if it so, which ...
- 161
2
votes
0
answers
52
views
How to quantitively compare two seismic waveform data?
Our group has built an Arduino-based device with an MPU6050 to act as our seismometer for our project, with the data being displayed on Amaseis. Our proctor demands that we quantitively assess its &...
- 21
0
votes
0
answers
19
views
Estimation of velocity of the wave from seismic trace
How can seismologists estimate velocity (on the different layers) of the wave propogated through the earth , only from given seismic trace(s) ?
1
vote
0
answers
19
views
If deterministic wavelet is better for well ties , why do people use statistical wavelet too for wellties?
Synthetic trace generated with deterministic wavelet gives a higher correlation with real seismics.
Though it's more accurate for seismic well ties than statistical wavelet, but there is always an ...
5
votes
1
answer
78
views
What is the purpose of wavelet extraction from the seismic trace?
I would love to know what exactly we can do with the extracted wavelet. What kind of information extracted wavelet can contain?
3
votes
1
answer
86
views
Predicting rock type from seismic processing
In reflection seismology, we create a source with an airgun and then use receivers to register acoustic waves (an approximation) at the surface. From these measurements, we can predict a velocity ...
- 133
5
votes
1
answer
107
views
Is there a seismic discontinuity between the lithosphere and asthenosphere?
I've been learning about seismic discontinuities, mainly the 5 defined ones - Conorod discontinuity, Mohorovicic discontinuity, Repetti discontinuity, Gutenberg discontinuity, and Lehmann ...
4
votes
0
answers
35
views
Seismicity associated with post glacial rebound
Allied to the question: Why is relative sea-level falling in Hudson Bay?, where the surviving answers mention post glacial rebound.
Is seismicity associated with post glacial rebound and if so what is ...
- 23.1k
0
votes
0
answers
39
views
Are there specific layers in the subsurface that come before gas or oil?
Currently, I've started working on a geophysics project. More specifically, I'm trying to find gas and oil reservoirs in SEGY files using deep learning. I've been reading about seismic reflection ...
- 9
1
vote
0
answers
56
views
What are the boundary conditions for Navier's Equations of motion in seismic?
Navier's equations of motion in seismic have 3 solutions, according to how it is resolved (boundary conditions):
for Vp (compression waves)
for Vs (shear waves)
for Vr (Rayleigh waves)
I know the ...
- 111
0
votes
0
answers
30
views
Preconditions for stacking
Some of the requisite for stacking is that the noise and amplitudes need to be uncorrelated. Can someone explain to me why?
Also is there a drawback for stacking?
- 11
1
vote
0
answers
48
views
Quality control in Seismic Acquisition - shot offset shift
I have a problem with seismic data where the minimum offset of the shot is not centered at the nearest receiver, this shift can be for 3 traces 2 or one and maybe more in the two sides !!
So is there ...
- 41
1
vote
0
answers
20
views
Conversion of SEG-Y relative to MSL
I am working on the conversion of CSF file from SonarWiz into SEG-Y data. However, it comes back always related to the Sensor depth/altitude and never to the MSL.
I have tried changing the bytes from ...
2
votes
1
answer
71
views
Recent high seismic activity in Europe
It seems that Europe and the Mediterranean Sea have had high seismic activity in last six months. Major events which I remember are:
2020 Aegean Sea earthquake, magnitude of 7.0 Mww
29 December 2020:...
- 23
1
vote
1
answer
98
views
What would be the phase shift and polarity of a seismic wave upon reflection
What would be the phase shift and polarity of a seismic wave a) when it hit the free surface
b)when the free surface reflection goes down and hit a reflector and returned to the receiver placed on the ...
- 111
4
votes
0
answers
141
views
Beam forming FK analysis of a seismic wave
So after reading alot of literature on source localization, I found out that FK analysis is one of the most widely used methods to determine source location without explicitly calculating the ...
- 141
1
vote
0
answers
54
views
How does uplift lead to onlapping?
I read in a paper that:
Interpretation of 2-D seismic lines shows the lower to middle
Patchawarra Formation onlapping onto paleostructural highs at
approximately 270 Ma and again at 273 Ma, ...
- 11
1
vote
1
answer
632
views
How do we know the speed of S-waves (shear waves) in the Earth's inner core? Has this been measured?
Wikipedia's Seismic wave includes the plot below of the speed of S and P waves as a function of depth in the Earth. In the region of the outer core the speed of S-waves or shear waves is shown to be ...
- 6,942
1
vote
1
answer
62
views
Q factor estimation from VSP
in seismic data processing there is a step of calculating the absorption represented By Q value which is Q factor , how we can estimate it from VSP !
thank you.
- 41
2
votes
3
answers
176
views
stretch phenomena after NMO application on seismic data
after the NMO application we have stretch for far offset , i read a lot of articles but i can't have a complete idea how this phenomena is really created ! any one have a rich explanation ?
- 41
0
votes
1
answer
95
views
Where can I find broadband seismic reflection data?
or what type of companies should I contact to ask for the data?
This data would be produced from Seismic Vibroseis survey trucks which are mostly used to locate oil and gas.
I doubt most oil and gas ...
3
votes
1
answer
1k
views
Why do P waves have a higher velocity in the lower mantle than in the core even though the core has a much higher density?
I've just started teaching 9th grade Earth science and my students and I have noticed something about P and S wave depth vs velocity graphs. In the typical graph,
eg: https://www.researchgate.net/...
- 31
0
votes
1
answer
139
views
Hydrophone/geophone sensor sensitivity - noise versus signal
Today, a student asked this question, and I was unable to answer it in a way that was understandable and accurate - even for myself.
For seismic data acquisition projects, how are sensors able to '...
- 741
2
votes
1
answer
125
views
Using an accelerometer as a geophone to conduct a seismic survey
I am doing a capstone project for a sensor systems course and I would like to write a python program to acquire, process and present seismic data like that of seismic surveys. Is it possible using ...
- 21
1
vote
0
answers
127
views
Finding out actual dip and dip direction of refractor
We have two traveltive curves for first arrivals (direct and refracted) from a dipping refractor in the forward and reverse directions along a profile line.
my question is:
Is there a logical way (non-...
3
votes
2
answers
92
views
Is it reasonable to approximate the swinging building (base of the building) during an earthquake to a simple harmonic motion?
I am thinking of making a model of swinging building during earthquake and study the methods to minimize the swinging.
So does it even makes sense to approximate the swinging buildings (the base of ...
- 31
4
votes
0
answers
46
views
Seismic velocity inversion & analysis
I attended at talk recently at the TGS office in Houston, TX, by Marianna Raunch. During this talk, a statement was made that for "very large" velocity inversions, semblance (or other similar ...
- 741
3
votes
1
answer
109
views
Wave train 200 m/s meaning
I ran a 60 m line intended for surficial seismic refraction. Energization with hammer. 12 (10 hz vertical 5 m spaced) geophones and 5 shots (15 m spaced). Record length 0.5 s. Thanks to a borehole ...
4
votes
1
answer
176
views
wavelength of seismic wave with a gaussian source
I want to know how to get the wavelength/frequency of a seismic wave, if I only have a Gaussian source and the velocity (c = 4000m/s) of a medium given.
e.g. for a Ricker wavelet it would be easy to ...
- 41
2
votes
1
answer
40
views
Seismic amplitude distribution
Recorded (or raw) and processed pre/post-stack seismic data (relative amplitudes) usually display a standard normal distribution, albeit with a very small amount of skewness.
What would be possible ...
- 741
1
vote
1
answer
37
views
Seismic wavefield theory: velocity anisotropy
Does the reciprocity principle hold true in an anisotropic subsurface environment?
- 741
2
votes
1
answer
97
views
What is the vertical axis of this waveform shown in this tweeted IRIS GIF?
This IRIS tweet shows a video of siesmic waves from the recent M6.4 Earthquake in California rolling across the US.
I've made a small GIF to give the idea but the "GIF" in the tweet shows the whole ...
- 6,942
1
vote
1
answer
139
views
How to read Seismic Survey?
Recently I am tasked to create a POC on detection of patterns using a neural .
But I am from a computer science background so I know about neural networks but I don't have any knowledge about geology ...
- 113
1
vote
1
answer
167
views
wave speed is smaller than both horizontal wave speed and vertical wave speed?
I am new to GIS and just get the idea of slowness. I can understand why people need the slowness in GIS rather than just the reciprocal of velocity. However, I feel the definition of slowness is weird ...
- 11
1
vote
1
answer
147
views
reverse time migration for wave equation PDE using SBP-SAT
I'm stuck implementing a reverse time migration technique, the PDE(partial differential equation) being implemented is an acoustic wave equation, The numerical method being used is a FD(finite ...
- 11
3
votes
2
answers
1k
views
Travel Times for Seismic Wave Types - Why reflected t-x plot curves
I do not understand how the reflected wave in a seismic survey has a steepening slope (slows down) Please bear with me as I lay out my thoughts because I feel like I can grasp all of this except this ...
- 303
0
votes
1
answer
92
views
Near-Surface Investigations: FWI vs. MASW
MASW is a common processing method for civil/geotechnical and even for oil/gas exploration (usually weathering static corrections) applications. In my experience, it seems to work well for most ...
- 741
4
votes
0
answers
76
views
Seismic data acquisition: reliability of high-bandwidth data
In my research, finding and understanding info relating to the lower end of (conventional) surface seismic data acquisition (i.e. 15 - 1 Hz) is relatively simple. However, when I look at specs for a ...
- 741
1
vote
1
answer
69
views
Love-Wave Propagation
Love-waves cannot exist in a half-space. Layering must be present and there also must be accompanied impedance contrasts associated with the layering.
Because layering naturally induces seismic ...
- 741
3
votes
0
answers
65
views
Difference between landslide waves and earth quake waves
I am new to this field, recently started working on landslide monitoring mainly in signal processing part. I have the following questions?
1.Will each land slide and every vibration have p wave, s ...
- 31
1
vote
1
answer
428
views
Quality control in Seismic Acquisition - How much data is required?
When it comes to land or marine acquisition (oil exploration, for instance), I can see from literature that quality control (QC) is performed during the survey to ensure that the seismic traces ...
- 141
2
votes
2
answers
2k
views
converting segd data to SU format using seismic unix
I tried to convert segd format to su format using seismic unix by below command:
segdread tape=1.segd > 1.su
but I have an error:
...
- 21
2
votes
1
answer
91
views
Basic petrophysics
The following question was inspired by Effective pressure or what is the effect of presssure?, which may be accessed here: https://inside.mines.edu/UserFiles/File/CRA/2005/...
- 741
2
votes
1
answer
236
views
DC component in Hilbert transform concept for seismic data
In The Leading Edge tutorial article Phase and the Hilbert transform (Purves 2014), there is the following line:
So we apply a Hilbert transform by multiplying all negative frequencies by i and all ...
- 741
5
votes
0
answers
55
views
How do I generate a Moho depth model from seismic refraction data?
There are several permanent seismograph stations in Eastern Canada that have been recording arrival times for over 25 years. Using refracted Pn arrival times from natural earthquakes I would like to ...
1
vote
1
answer
119
views
Spectral Whitening, Seismic Interferometry
What is the role of spectral whitening in the processing step done before cross-correlations in seismic interferometry?
- 11
1
vote
0
answers
72
views
Seismology - PPV / VDV from geophone waveform data
I'm using an inexpensive seismometer to try and measure the effects of local HGV traffic on buildings. The device is connected to a Raspberry PI that has a Cirrus Logic Audio Card. The signal is fed ...
- 111
3
votes
2
answers
2k
views
Seismic dispersion: What does it really mean and what causes it?
Body waves (to some extent) and especially surface waves show dispersive characteristics during propagation. In Dr. Christopher Liner's book [Elements of Seismic Dispersion (2012)], this phenomenon is ...
- 741
1
vote
1
answer
80
views
What does 'reghosted' mean in a seismic cube label?
I came across to a seismic volume labeled as reghosted. In my understanding, a seismic survey is deghosted as part of a processing step. Then I wonder why one would like to reghosted the data? Is ...
- 31
3
votes
0
answers
45
views
Which wavelet for acoustic inversion?
If I have seismic data obtained with an explosive source (i.e. minimum phase wavelet), should I re-process the data into zero-phase data to perform an acoustic impedance inversion?
- 31